Phineas and Ferb, Season 4

Phineas:
[walks towards Isabella] Watcha doin'? Hehe... [Isabella then smiles at him] Is this step taken? [referring to the steps at Phineas' house where Isabella is sitting]

Isabella:
[allows Phineas to sit beside her] I actually came by to say goodbye to you.

Phineas:
Off to school, huh.

Isabella:
Yeah, I'm going two weeks early because I'm an RA, and in soccer, debate camp, student government.

Phineas:
Yeah. I haven't seen you all summer.

Isabella:
I've been busy. [Isabella pauses]

Phineas:
You know, Baljeet said something funny. He said you had a crush on me back in grade school.

Isabella:
Oh! Yeah, I had a big crush on you.

Phineas:
Well, I had no idea.

Isabella:
Really? I thought I was being so obvious.

Phineas:
Absolutely clueless. Sorry. [Phineas pauses]

Isabella:
I sort of gave up when we got to high school.

Phineas:
Yeah. I think that's when I started having a thing for you.